This invention relates to a steam iron with a pump mechanism according to the prior-art portion of patent claim 1.
From U.S. Pat. No. 3,691,660 a piston pump for a steam iron is known which feeds pumped water either to a water spray or to an extra burst of steam. The two liquid consuming devices involving the water spray and the extra burst of steam are selected in dependence upon the rotary position of a common actuator, with the same actuator being depressed to direct the liquid pumped into a pressure-generating chamber by means of an axially movable piston to one of the liquid consuming devices. For opening one of the outlets provided on the pump housing in dependence upon the rotary position of the actuator while the other outlet is maintained closed, a distributor element is inserted in a cavity of the pump housing. The distributor element is connected with the actuator in a manner preventing relative rotation and has a central bore and a radial bore extending to one side, so that the pumped liquid is directed through the central bore and the radial bore to one of the outlets. Considering that the outlets are arranged opposite each other at the same level on the pump housing, this piston pump requires plenty of mounting space in the steam iron. Further, the complex structure of this piston pump makes it relatively elaborate to manufacture, requiring relatively high manufacturing accuracy particularly in the area of the outlets between the circumferential surface of the distributor element and the opposite inner surface in order to provide an easily rotating distributor element on the one hand and a tight seal for the outlet to be closed on the other hand.
A piston pump similar to this one in respect of its basic structure is known from European patent application 497 470. In this application, two outlets equally arranged opposite each other at the same level on the pump housing are supplied with pumped liquid through a distributor element arranged both rotatably and axially displaceably in the interior of an axial housing bore. The circumferential surface of the distributor element is configured such that only one outlet at a time is opened, depending on the distributor element's rotary position. In this event, the end of the distributor element forms at the same time the piston, so that the pressure-generating chamber is formed by the cavity defined between a ball valve at the inlet of the housing bore, the piston upper surface, and a ball valve at the outlet. The dual function of the distributor element which includes the added piston function has, however, the disadvantage that a seal relative to the distributor element and the outlet to be closed demands a major manufacturing effort, because the seal is required to be effective during both rotation and longitudinal displacement of the distributor element.
From EP 0 694 646 A1 a steam iron is known which incorporates a common pump mechanism for two liquid consuming devices. An axially movable piston has a central bore communicating with one of the two liquid consuming devices in dependence upon which of the two push-buttons is pressed. By pressing one of the push-buttons, the piston is displaced on the one hand, while on the other hand a seal is urged into sealed engagement with a supply conduit leading to the non-selected liquid consuming device. As a result of the eccentric arrangement of the two push-buttons, the housing wall guiding the piston axially is subjected to one-sided wear. Moreover, this system is susceptible to incorrect operation because the two push-buttons are arranged closely side-by-side.
A steam iron with a pump mechanism of the type initially referred to is known, for example, from applicant's PV 1210 series of steam irons. FIG. 5 illustrates a longitudinal section through a piston of such a pump mechanism. This piston is axially movably mounted in a housing bore of a pump housing, not shown, for compressing a pressure-generating chamber. The piston has an axial distributor bore in which a distributor element is inserted. The distributor element has its upper end area connected with an activating element, so that an operator, in using the same activating element, displaces the piston axially by a pressing motion and the distributing element by a rotating motion.
The distributor element includes further a central conduit opening into a connecting conduit at the frontal bearing surface of the distributor bore. The connecting conduit of the piston communicates with the pressure generating chamber through a ball valve. The central conduit of the distributor element has its upper end connected with an outlet for the water spray through a radial bore, in addition to having its mid-region connected with an outlet for the extra shot of steam through another radial bore. The two radial bores of the distributor element are disposed in a 180.degree. offset relation to each other.
The distributor element of the known piston pump includes two seals arranged above and beneath the upper radial bore on the circumference of the distributor element. The distributor element is surrounded by a non-rotatably mounted sleeve having an opening each in the area of the two outlets. The sleeve and the distributor element are made of stainless steel, with the inside diameter of the sleeve and the outside diameter of the distributor element being relatively coordinated and manufactured to close tolerances in order to obtain a tight seal between the two outlets while at the same time ensuring ease of rotation of the distributor element. Accordingly, the manufacture of the known piston pump has the undesired effect of necessitating a relatively high production effort.
It is therefore an object of the present invention to provide a piston pump of the type initially referred to which involves less manufacturing effort and has in particular tightly sealed fluid paths without the need to specify close manufacturing tolerances for this purpose.